(;AW[cr]AW[ds]AW[aq]AW[bq]AW[bp]AW[bo]AW[ao]AB[am]AB[bm]AB[cn]AB[co]AB[cp]AB[cq]AB[dq]AB[er]AB[es]AW[bs]AB[dr]AW[as]C[Black to get the best result]AP[goproblems]
(;B[br]
(;W[ar];B[cs]C[A favorable ko is indeed the best Black can getCHOICERIGHT])
(;W[cs];B[ar]C[RIGHT]))
(;B[cs];W[br])
(;B[ar];W[br]))